Combination yard maintenance apparatus

ABSTRACT

A combination yard maintenance apparatus used for lawn mowing, leaf clearing and snow blowing comprises a blade assembly having an elongated support member for rotatably mounting to a drive shaft and two shovelling surfaces disposed at opposite ends of the elongated support member extending from the elongated support member downwardly and laterally opposite one from the other. Each shovelling surface has a lower edge with a cutting edge, an upper edge, an inner edge and an outer edge. The present invention also provides a clutch mechanism for engaging and disengaging an input shaft from an output shaft comprising a first and a second threadable engagement associated with the input shaft and output shaft respectively, and an initiator for inducing the engagement of the first and second threadable engagements. A friction-drive self-propelling system is also provided, comprising a driving wheel and a friction disk wherein the driving wheel has central recessed portion.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to U.S. Provisional Application No. 60/811,100 filed Jun. 6, 2006.

FIELD OF INVENTION

This invention relates to a combination yard maintenance apparatus which is especially useful but not limited to mowing grass, clearing leaves and blowing snow.

BACKGROUND

The tasks of mowing grass, blowing snow and clearing leaves or the like typically require three different pieces of equipment, namely a lawn mower, snow blower and leaf blower. This obviously requires a large amount of storage space and can incur significant purchase and operating costs.

There are various multi-use devices that have been proposed for cutting grass and blowing snow. Canadian Patent No. 2,133,548, for example describes a snow blower attachment for lawnmowers that is used for clearing snow and other particulate material. This enables the lawnmower to be used for clearing snow during the winter, when it cannot be used for cutting grass. This particular apparatus comprises one or a pair of arms mounted for rotation within the housing of a conventional rotary lawnmower or equivalent, as a substitute for the grass-cutting blade. The rotatable arm comprises an elongated blade member having upper and lower vanes extending upwardly and downwardly respectively from the blade member. The lower vanes act as knives to cut the snow or material to facilitate removal. The upper vanes direct material above the blade outwardly through a discharge opening of the housing.

Canadian Patent No. 695,405 also describes a combination lawnmower and snow remover which may be used for the purpose of mowing grass or for the purpose of snow removal without any adaptation. The apparatus comprises a housing in which an inverted upper frustro conical member is mounted for free rotation. Securely attached to the upper frustro conical member and positioned below on a common axis is a lower frustro conical member. At least one blade projecting outwardly is attached in a spiral manner to the outer surface of the lower frustro conical member. A cutting edge is provided at the lower end of the blade.

Self-propelling mechanisms comprising a driving wheel and a driven friction disk are commonly used in conventional lawnmowers and snow blowers. One important source of wear of the friction disc results from the friction disc contacting the driving wheel at the center or neutral axis resulting in flat portions being ground on the friction disc.

Some methods have been proposed for eliminating wear of the friction disk at the neutral position. For example, U.S. Pat. No. 4,169,392 describes a self-energizing friction drive transmission which includes a conventional drive disc rotatable about a vertical axis and a vertical friction disc engaging the top horizontal face of the drive disc to be driven about a horizontal axis. In this particular case, the problem has been solved by providing a configured control plate which simply raises the friction disc away from the drive disc when the friction disc is over the center or neutral axis of the drive disc.

Another common problem with current self-propelling mechanisms of this type is that they can produce a significant amount of heat especially when used continuously for long periods of time. The excessive heat in turn accelerates the deterioration of the disks and thereby shortens the lifetime of the drive unit.

SUMMARY OF THE INVENTION

According to one broad aspect, the present invention provides a blade assembly for rotatably mounting to a yard maintenance apparatus. The blade assembly may be used for mowing grass, blowing snow or clearing leaves or the like. The blade assembly comprises an elongated support member for rotatably mounting to a drive shaft of the yard maintenance apparatus and two shovelling surfaces disposed at opposite ends of the elongated support member extending from the elongated support member downwardly and laterally opposite one from the other. Each of the shovelling surface has a lower edge with a cutting edge, an upper edge, an inner edge and an outer edge.

Preferably, the blade assembly may also comprise an upwardly extending vane. The vane may further extend outwardly beyond the outer edge of the shovelling surface. Similarly, the cutting edge of the lower edge of the shovelling surface may also extend outwardly beyond the outer edge of the shovelling surface.

The shovelling surface may be planar or have a curved or rounded profile such as parabolic. Preferably the outer edge of the shovelling surface has a circular vertical projection. The shovelling surface of the blade assembly may also have an outer flange with a cutting edge.

Advantageously, the present invention also provides a blade assembly wherein the shovelling surface is divided into a first stage and a second stage. In this configuration, the blade assembly may preferably have a first stage defining a curved or parabolic shovelling surface portion and a second stage defining a planar shovelling surface portion.

According to another aspect, the present invention provides, a combination yard maintenance apparatus for lawn mowing, leaf clearing and snow blowing which comprises a blade assembly configuration as described above; a chassis having ground wheels, an inlet and a discharge outlet; a motive power source mounted on the chassis; a drive shaft coupled to the power source and extending along a vertical axis wherein the blade assembly is coupled to the drive shaft.

Preferably, the chassis of the combination yard maintenance apparatus also comprises a cylindrical portion having a vertical longitudinal axis in which the blade assembly is rotatably mounted. Advantageously, the combination yard maintenance apparatus may also comprise a discharge outlet having a movable deflector for changing the discharge direction.

Preferably, the combination yard maintenance apparatus may also have a clutch mechanism for engaging and disengaging the blade assembly from the drive shaft.

Preferably, the combination yard maintenance apparatus may also have a self-propelling mechanism.

According to a further aspect, the present invention provides a clutch mechanism for engaging and disengaging an input shaft from an output shaft. The clutch mechanism comprises: a first threadable engagement associated with the input shaft; a second threadable engagement associated with the output shaft and an initiator for inducing the engagement of the first and second threadable engagements.

Preferably, the first threadable engagement comprises an externally threaded portion on the input shaft; and the second threadable engagement comprises an output driver having an internally threaded portion. As such, the first threadable engagement is engaged to the second threadable engagement when the rotation of the input shaft relative to the output shaft is in a working direction.

Preferably, the clutch mechanism may further comprise a drive head connected to the input shaft such that when the output driver is fully engaged to the input shaft, the drive head is in contact with the output driver via corresponding mating surfaces. The corresponding mating surfaces may define a one-directional locking system which prevents further rotation of the drive head in the working direction relative to the output driver. Preferably, the one-directional locking system may comprise a step defined on the mating surface of the drive head and a cooperating step defined on the mating surface of the output driver.

Advantageously, the initiator of the clutch mechanism may be cable-activated and may comprise a cable attached to a riser that is in contact with the output driver wherein the riser is also in biased contact with a stator. As such, movement of the riser relative to the stator causes movement of the output driver and induces the engagement of the first and second threadable engagements.

Preferably, the riser may be in rotatable contact with the stator about a central axis and the mating surfaces between the riser and the stator can be adapted such that rotational movement of the riser about the central axis relative to the stator causes longitudinal movement of the output driver along the central axis.

According to yet another aspect, the present invention also provides a friction-drive self-propelling system comprising a driving wheel coupled to a motive power source; the driving wheel having a driving surface normal to its axis of rotation wherein the driving surface has a central recessed portion. The self-propelling system also has a driven friction disk having an axis of rotation transverse to the axis of rotation of the driving wheel and having an outer peripheral surface being tangentially engageable with the driving surface. The friction disk is laterally movable along its axis of rotation between a neutral position and a propelling position such that in the neutral position, the friction disk is aligned with the central recessed portion and thereby disengaged from the driving surface. Preferably, the driving wheel may also comprise one or more radial fins.

Preferably, the friction-drive self-propelling system may further comprise a tension adjustment for adjusting a force of engagement between the driving wheel and the driven friction disk.

Advantageously, the speed of rotation of the driven friction disk can be adjusted by lateral movement of the driven friction disk thereby altering the distance between the propelling position and the central recessed portion of the driving surface.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a perspective view of a yard maintenance apparatus according to one embodiment without the motive power source.

FIG. 2 shows a perspective view of a single-stage blade assembly according to one embodiment.

FIG. 3 shows a top plan view of the single-stage blade assembly of FIG. 2.

FIG. 4 shows a perspective view of a single-stage blade assembly according to another embodiment.

FIG. 5 shows a top plan view of the single-stage blade assembly of FIG. 4.

FIG. 6 shows a perspective view of a double-stage blade assembly according to one embodiment.

FIG. 7 shows a top plan view of the double-stage blade assembly of FIG. 6.

FIG. 8 shows a cross-sectional side elevation view of a clutch according to one embodiment in a disengaged state.

FIG. 9 shows a cross-sectional side elevation view of the clutch of FIG. 8 in an engaged state.

FIG. 10 shows a side elevation view of a clutch engagement mechanism in the engaged state.

FIG. 11 shows a cross-sectional view of the clutch engagement mechanism along line A-A of FIG. 10.

FIG. 12 shows a perspective view of a rear side of the yard maintenance apparatus of FIG. 1.

FIG. 13 shows a perspective view of an inlet cover for covering a front opening of the yard maintenance apparatus of FIG. 1.

FIG. 14 shows a perspective view of a rear cover for covering a rear discharge opening of the yard maintenance apparatus of FIG. 1.

FIG. 15 shows a perspective view of a side cover for covering a side discharge opening of the yard maintenance apparatus of FIG. 1.

FIG. 16 shows a perspective view of a funnel-shaped deflector for mounting to the front opening of the yard maintenance apparatus of FIG. 1.

FIG. 17 shows a perspective view of a vertical cutter bar.

FIG. 18 shows a perspective view of a discharge outlet.

FIG. 19 shows a perspective detailed view of a friction-drive self-propelling system according to one embodiment.

FIG. 20 shows a cross-sectional view of the friction-drive self-propelling system along line A-A of FIG. 19.

FIG. 21 shows a front elevation view of the friction-drive self-propelling system of FIG. 19.

FIG. 22 shows a perspective view of a speed control assembly of the friction-drive self-propelling system of FIG. 19 and a clutch control lever.

FIG. 23 shows a perspective view of a single-stage blade assembly according to a further embodiment.

FIG. 24 shows a top plan view of the single-stage blade assembly of FIG. 23.

FIG. 25 shows a perspective view of the single-stage blade assembly of

FIG. 23 positioned within a yard maintenance apparatus according to another embodiment.

DETAILED DESCRIPTION

Referring particularly to the drawings, the figures are for the purpose of illustrating embodiments of the invention only and not for the purpose of limiting same.

In FIG. 1, a combination yard maintenance apparatus 1 which is especially useful but not limited to mowing grass, clearing leaves and blowing snow is shown. The yard maintenance apparatus 1 comprises a chassis 4 with a cylindrical cavity 19 and a relatively light weight blade assembly that is rotatably mounted inside the cylindrical cavity 19 of the chassis 4. Different blade assembly configurations suitable for mounting into the chassis are shown as elements 161, 162 and 163 in FIGS. 2-7 and element 193 in FIG. 23. The yard maintenance apparatus 1 also has a push handle 11, two front wheels 2, and two rear wheels 3 wherein the height of the wheels 2 and 3 may be adjusted relative to the chassis 4. An engine brake bar control 57 and a brake-line cable 58 are also shown.

The annular platform 9 at the top of the chassis 4 is adapted to support a motive power source that is coupled to a vertical drive shaft 36 that extends downwardly into the center of the cylindrical cavity 19. The motive power source is not shown here for the sake of clarity. However, a suitable conventional electric motor or gasoline engine may be used. Preferably, a four-stroke gasoline engine with at least 6 hp is recommended.

The chassis 4 comprises three openings: a front opening 160, a rear opening 164 and a side opening 165 which are both shown in FIG. 12. The front opening 160 is used for intake of snow, grass, leaves or the like. However, when the yard maintenance apparatus 1 is used for cutting grass, the front opening 160 may be covered with an inlet cover 60 such as shown in FIG. 13.

The rear opening 164 and side opening 165 are utilized for discharge. The side opening 165 and the rear opening 164 can either be covered or uncovered in various combinations such as to accommodate mulching, side-discharge onto the ground, or rear-discharge into a collection bag (not shown). A rear cover 14 shown in FIG. 14 with flanges 15 and holes 16 can be mounted to the chassis 4, such as to cover the rear opening 164, by tightening nuts (not shown) on the four studs 8. Similarly, a stopper plate 17 shown in FIG. 15 with a flange 18 can be used for covering the side opening 165 by inserting the stopper plate 17 into the slot 6 and securing it to the studs 7 (see FIG. 1).

The multi-purpose blade assembly is used to perform the actions of cutting, shovelling, and propelling of particulate. There are several ways in which the multi-purpose blade assembly of the present invention may be configured. For example a single-stage blade assembly 161 is shown in FIGS. 2-3, an alternate embodiment of a single-stage blade assembly 162 with taller and wider flanges is shown in FIGS. 4-5, and, a further embodiment of a single-stage blade assembly 193 is shown in FIGS. 23-25. A double-stage blade assembly 163 is shown in FIGS. 6-7. Multi-stage blade assemblies (not shown) having more than two stages may also be used.

The single-stage blade assembly 161 shown in FIGS. 2-3 comprises a blade axle 20, an elongated support member 25 and two blades 166. The various blade assemblies described may be made of any suitable material such as steel, aluminum or a combination thereof. The elongated support member 25 comprises a rectangular tube with support seatings 27 at both ends on which the blades 166 are fastened with rivets 28. Other cross-sections such as a U-channel may be used for the elongated support member 25, however rectangular tube is superior in resisting torsion induced by the actions of the blades 166. The blade axle 20, is connected to a rectangular drive head 21 with a key 22 and is secured inside a central opening in the elongated support member 25 by two screw, nut and spring washer sets 23. The elongated support member 25 is further secured to the rectangular drive head 21 with an additional screw and spring washer set 24 threaded directly into the blade axle 20.

The blades 166 comprise an inclined and planar shovelling surface 33 with a horizontal cutting edge 30 along the lower edge of the shovelling surface 33. The angle of inclination of the shovelling surface 33 may preferably range from 55 to 60 degrees from horizontal. The blade 166 also has an outer flange 167 having a cutting edge 31 along the outside edge of the shovelling surface 33, and an inner flange 168 having a cutting edge 32 along the inside edge of the shovelling surface 33. The addition of the outer flange 167 and/or inner flange 168 also provide additional rigidity to the shovelling surface 33 to prevent bending during use. A stiffening plate 29 is also welded to the bottom of the elongated support member 25 to provide additional support. A vertical vane 26 is attached to each blade 166 at the top edge of the shovelling surface 33.

The outside edge of the blade 166 and flange 167 may have a linear profile or a circular vertical projection which more closely conforms to the profile of the cylindrical cavity 19 of the chassis 4. This feature is clearly shown in FIG. 3 and provides an effective way of scooping up and expelling the particulate through one of the discharge openings.

During use, the rotary action of the blade assembly 161 causes the blades 166 to serve as shovels and move the particulate up the shovelling surface 33. Due to centrifugal forces induced on the loose particles, the vanes 26 propel and direct the particulate outwardly towards a desired outlet. The outer flange 167 and inside surface 169 of the cylindrical cavity 19 together act as a guard to prevent the loose particles from flying off the blades 166 prematurely.

FIGS. 4-5 show another embodiment of the single-stage blade assembly 162. One main difference between the two designs is that instead of being planar, the shovelling surface 33 has a curved profile. This feature improves the efficiency of the shovelling action of the blade 166. Further, the outer flange 167 and the inner flange 168 are much wider and taller. The wider and taller flanges 167 and 168 prevent the outward radial airflow from obstructing the intake of the particulate. The taller outer flange 167 also improves in the guiding of the flow of materials upward.

The horizontal cutting edges 30 of the blades 166 are primarily used to cut grass while the cutting edges 31 and 32 along the outer and inner flanges 167 and 168 respectively are used for mulching. In the process of clearing leaves or other similar debris, the inlet cover 60 for the front opening 160 may be replaced by a funnel-shaped deflector 63 shown in FIGS. 12 and 16 to facilitate the intake of leaves. Both cutting edges 30 and 31 should be relatively sharp to be most effective as they chop and break up the leaves into small pieces for swift transport and better compaction. A perforated bag (not shown) may be adapted to the rear opening 164 for leaf collection.

During the leaf clearing process and as an option, a bar 34 with slotted holes 35 and vertical right angle sharp edges 170 shown in FIG. 17, can be installed in the clearance between the inner surface 169 of the cylindrical cavity 19 and the cutting edges 31 of the blade assembly. The bar 34 is fastened using nuts and bolts through mounting holes 5 on the chassis 4 shown in FIG. 1 and is used to break down the leaves or similar debris more efficiently. The sharp edges 170 on the bar 34 cooperate together with the cutting edges 31 of the blade assembly and mimic a scissor-like cutting process.

During use, care must be taken by the operator to prevent the blade assembly from hitting hard objects such as large branches, rocks or chunks of ice.

For snow blowing tasks, the funnel-shaped deflector 63 is also used to facilitate the intake of snow into the front opening 160. The funnel-shaped deflector 63 is sufficiently wide to direct snow ahead of the front wheels 2 into the front opening 160 thus keeping the front wheels 2 clear and reducing resistance while advancing forward. The funnel-shaped deflector is adapted with stiffeners 64-66 that provide structural rigidity. The rear opening 164 should also be closed using the rear cover 14. The blade assembly 161, 162 or 163 first break up the snow, shovel it upwardly and expel it through the side opening 165. The side opening 165 leads into a discharge outlet 171 shown in FIG. 18 which comprises a movable deflector 50 capable of deflecting exiting materials in a desired direction.

A scraper plate 87 shown in FIG. 12 can also be fastened to the chassis 4 using bolts 88 to cover the rear half of the bottom of the cylindrical cavity 19. The scraper plate 87 collects the snow between the ground and the chassis 4 and pushes it back inside the cylindrical cavity 19 for clearing by the blades. The height of the scraper plate 87 can be adjusted to set the ground clearance accordingly.

FIGS. 23-25 show a further embodiment of a single-stage blade assembly 193. In this embodiment, each blade 166 comprises a shovelling surface 33, an inner flange 168, an outer flange 167, a horizontal cutting edge 30 and a vane extension 12 secured to a vane 26 using rivets 28. Evidently, any other suitable means of securing the vane extension 12 to the vane 26 may also be used. For example, the vane extension 12 may be welded to the vane 26 or, alternatively, the vane 26 and the vane extension 12 may be integrally formed into a single component.

As shown in FIG. 24, each shovelling surface 33 is disposed at a distance from the inside surface 169 of the cylindrical cavity 19 of the chassis 4. Accordingly, the horizontal cutting edge 30 and the vane extension 12 extend outwardly beyond the outer flange 167 in order to more closely conform with the inside surface 169 of the cylindrical cavity 19. The outer flange 167 has a non-linear transverse profile as shown in FIG. 24. Each blade 166 is secured to the elongated support member 25 using a support seating 27 and an angle bracket 182. The support seating 27 is fastened to a back side of the vertical vane 26 by rivets 28 and the angle bracket 182 is affixed to an underside of the shovelling surface 33 by rivets 28. Both the support seating 27 and the angle bracket 182 are anchored to the elongated support member 25 with bolts 181. Again, other suitable means of securing the blades 166 to the elongated support member 25 may be used.

FIG. 25 shows the single-stage blade assembly 193 in an operating position within a yard maintenance apparatus 194 according to another embodiment. In this embodiment, the cylindrical cavity 19 is divided into a lower portion 195 and an upper portion 191 by an annular flange 13. A top cover 192 is also provided to cover the upper portion 191 of the cylindrical cavity 19.

During operation, the vanes 26 and the vane extensions 12 rotating inside the upper portion 191 above the annular flange 13, and covered by the top cover 192, perform in a manner similar to a pump structure thereby propelling the air together with the particulate material out of the rear opening 164 or the side opening 165. As described previously, the side opening 165 leads to the discharge outlet 171 shown in FIG. 18 and the rear opening 164 may lead to a perforated bag for collection (not shown).

One advantage of the single-stage blade assembly 161, 162 and 193 is that it is relatively simple to manufacture in comparison with the double-stage blade assembly 163 shown in FIGS. 6-7. However, the height of the front opening 160 for the intake of materials may be limited when using a single-stage blade assembly. Alternatively, the double-stage blade assembly 163 can be used to accommodate a higher front opening. The double-stage blade assembly 163 can also be further expanded to three or four stages simply by adding more intermediate blade sections and thereby allowing for an even higher front opening 160 and a larger amount of material to be removed at a faster rate.

The first stage 172 of the double-stage blade assembly 163 may comprise a planar or curved shovelling surface 133, an outer flange 131 and an inner flange 132. The inner and outer flanges also provide plenty of sharp edges for cutting purposes. The horizontal cutting edge is numbered 130. Radial metal stiffeners 127 are used to strengthen the fan-like structure of the blade assembly 163.

The second stage 173 of the double-stage blade assembly 163 comprises a shovelling surface 135 which can also be planar or have a rounded profile, an outer flange 134 and an inner flange 136 which are similar to the flanges 131 and 132 of the first stage. The flanges 134, 136, 131 and 132 intersect their respective shovelling surface such as to create an intersection angle that is greater than 90 degrees and therefore aid in streamlining the flow of the particulate up the shovelling surfaces 133 and 135. The second stage 173 also comprises a vertical vane 126 that is mounted to the top of the shovelling surface 135.

The first stage 172 and second stage 173 of the double-stage blade assembly 163 are mounted to the axle 20 through collars 121 and keys 22. A bolt and spring washer set 24 is also fastened to the bottom of the blade axle 20. If a triple-stage system is desired, one can simply add an intermediate stage to a taller chassis 4 having a longer blade axle 20. In this case, the intermediate stage could have the same configuration as the first stage 172.

Whether a single-stage or a multi-stage blade assembly is used, the blade axle 20 should be connected to the drive shaft 36 via a clutch allowing the blade assembly to be engaged and disengaged to and from the drive shaft. A suitable clutch 174 for this purpose is shown in FIGS. 8, 9, 10 and 11. The clutch 174 is used for engaging and disengaging the drive shaft 36 to and from the blade axle 20.

The clutch 174 comprises a clutch housing 81 containing the clutch components and is secured to the chassis 4 using bolts 82. The clutch 174 also comprises an annular stator 80 attached to the clutch housing 81 and an annular riser 72 in rotatable sliding contact with the stator. Both the stator 80 and the riser 72 have the blade axle 20 extending therethrough. The interface between the riser 72 and the stator 80 consist of a lateral cut 86 inclined at an angle of about 15 degrees from the horizontal plane as shown in FIGS. 8 and 9. A cable clamp 73 and a spring 74 are tightly secured on the riser 72 by screws 83 and clamps 84. The cable clamp 73 is affixed to a clutch cable 76. A blade driver 70 is coupled to the blade axle 20 by means of a splined coupling 175 shown in FIGS. 10 and 11 such as to allow some longitudinal movement of the blade driver 70 relative to the blade axle 20 along the axis of rotation of the blade axle 20. The blade driver 70 also comprises an internally threaded portion 177 which is adapted to engage to an externally threaded portion 178 on the drive shaft. A drive head 37 is firmly attached to the drive shaft 36 by a rectangular key 38.

FIG. 8 shows the components of the clutch 174 in a disengaged state and FIG. 9 shows the components of the clutch 174 in an engaged state. During use, the gasoline engine should be started while the clutch 174 is disengaged. Once the engine is running, the operator can push the clutch control lever 59 shown in FIG. 1 which, in turn, pulls on the cable 76 to engage the clutch 174. The cable 76, riser 72 and the stator 80 serve as an initiator to initiate the engagement of the clutch. The pulling force in the cable 76 causes the riser 72 to rotate relative to the stator 80 along the lateral cut 86 and thereby cause the top surface 176 of the riser to move linearly along the axis of rotation of the blade axle 20. As a result, the riser 72 pushes the blade driver 70 towards the rotating drive shaft 36. Once in contact, the rotation of the drive shaft 36 causes the externally threaded portion 178 of the drive shaft 36 to threadably engage the internally threaded portion 177 of the blade driver 70 as shown in FIG. 9. A thin belleville spring 71 is disposed between the blade axle 20 and the engine shaft 36 to provide a smoother engagement.

Once the engine shaft 36 and the blade driver 70 make contact, the operator should release the cable 76 by releasing the clutch control lever 59 shown in FIG. 1. A spring 74, which is secured to the riser 72 and to the stator 80 via the screws 83 and the clamps 84, pulls the riser 72 and the cable 76 back to their initial positions shown in FIG. 8.

The drive head 37 and the blade driver 70 have cooperating steps 85 shown in FIG. 10 on their respective mating surfaces which create a one-way locking arrangement. When the clutch 174 is fully engaged, the locking arrangement prevents further rotation of the drive shaft 36 in the working direction relative to the blade axle 20.

The engine shaft 36 and drive head 37 transmit the torque from the engine to the blade driver 70 which, in turn, transmits the torque to the blade axle 20 via the splined coupling 175 shown in FIGS. 10 and 11. The blade axle 20 with an embedded disk 78 rotate freely on top of a thrust ball bearing 79. A pin 77 is inserted in the mid-height of the disk 78 and the blade axle 20 for safety.

In order to disengage the clutch, the brake-line cable 58 of the gasoline engine is released thereby stopping the engine. As the engine stops running, the drive shaft 36 will stop abruptly whereas the blade assembly 161-163 will continue to spin freely for some time due to its angular inertia. This causes the blade driver 70 to unthread itself from the drive shaft 36 and return to its initial disengaged position, resting against the riser 72 as shown in FIG. 8. Therefore, whenever the engine is shut down normally, the blade assembly 161-163 will automatically become disengaged from the engine shaft 36. This is a very desirable safety feature of the apparatus.

The discharge outlet 171 shown in FIGS. 1 and 18 is mounted to the chassis 4 of the yard maintenance apparatus 1 and comprises, a crank handle 40, linkage rods 41 and 45, a linkage joint 42, a cross head driver 46, a rectangular chute 47, a rectangle-to-circle adapter 48, a gear boot 49, and a movable deflector 50. Both the gear boot 49 and the deflector 50 are mounted to the rectangle-to-circle adapter 48. Rings 10 are used to support the crank handle 40 and the linkage rods 41 and 45. A stopper collar 54 prevents the linkage rods from sliding out of position. Prior to the clearing operation, the operator can select the pitch angle of the deflector 50 by adjusting a knob nut 51 at a connection 52 between the deflector 50 and the gear boot 49. During operation, the operator may turn the crank handle to select a discharge direction, the turning action is transmitted to the cross-head driver 46 and to the gear boot 49 thereby re-orienting the movable deflector 50. As the exiting granular material passes through the rectangular chute 47, the rectangle-to-circle adapter 48 and the angular deflector 50 it is accordingly directed into a desired direction.

The friction-drive self-propelling system 179 of the present invention is shown in FIGS. 12, 19-21. The system 179 comprises a set of belt 90 and pulleys 91 connected to a shaft 93 which delivers torque from the drive shaft 36 to a driving wheel 113 through an arrangement of spur gears 96 and 112. The driving wheel 113 has a driving surface 180 shown in FIG. 20. The driving surface 180 has a central recessed portion 143 which extends radially outwardly from the center of the driving surface to about ⅓ of the radius of the driving wheel 113. The shaft 93 is supported by a couple of rolling bearings 94 and 95 shown in FIG. 12. As shown in FIG. 20, the spur gear 112 is affixed on an axle 111 and is attached firmly to the driving wheel 113. The spur gear 112 and axle 111 are supported by a thrust bearing 116 housed in a casing 115 and fastened on a bridge 117. The vertical position of the bridge 117 can be adjusted using screws 114. There is one screw 114 on the right hand side and two screws 114 on the opposite side such that rotation of the bridge is prevented.

Both speed control cables 102 and 124 pass through nuts 145 and hollow screws 146 fastened to the frame 103 as shown in FIG. 21. The cables 102 and 124 are then directed through four small pulleys 105 rotatably mounted to the frame 103 via central bolts 107. The cable 102 is attached to one side of a bracket 108 to which a friction disk 110 is mounted using an anchor bolt 106. The cable 124 is similarly fastened to the opposing side of the bracket 108. The bracket 108 can freely slide horizontally along two round supporting bolts 125 serving as rails. The supporting bolts 125 are secured to flanges 104 by nuts 128 and spring washers 129. The range of motion of the brackets 108 is restricted by the flanges 104. The frame 103 is firmly secured to the chassis 4 near the rear wheels 3 using nut 99 threadably engaged onto threaded portion 98 and screws 107 and 114.

Prior to starting the engine, the friction-drive self-propelling system 179 should always be disengaged. Self-propelling of the yard maintenance apparatus 1 is achieved by moving a speed control lever 101 shown in FIG. 22. Once the engine is running, forward motion is achieved by moving the lever 101 forward such that the opposing end 151 of the speed control lever 101 pulls on the cable 102. The speed control lever 101 must first be pushed to the side clearing the notches on the position arc 100 while compressing a belleville spring 153. The speed control lever 101 can then be rotated about a pivot bolt 155 such as to be positioned at a notch representing a forward speed on the arc 100. Consequently, as the speed control lever 101 is moved, the cable 102 pulls and moves the bracket 108 and the friction disk 110 towards the left in FIG. 21. As the friction disk 110 makes contact with the left side of the driving surface 180 of the spinning driving wheel 113, the friction disk 110 starts turning due to the frictional engagement between the two. The friction disk 110 thereby drives the wheel axle 140 through its square-center sheath 109 and the square portion of the axle 141 as shown in FIG. 19. The spur gears 142 at both ends of the axle 140 turn a corresponding pair of spur gears (not shown) that are coupled to the two hind wheels 3 which results in motion of the yard maintenance apparatus 1.

Similarly, reverse motion of the yard maintenance apparatus 1 is accomplished by moving the speed control lever 101 backward to a notch designated as reverse motion in the arc 100 shown in FIG. 22. The arm of the speed control lever 101 pulls on the cable 124, which in turn pulls the friction disk 110 and the bracket 108 towards the right side in FIG. 21. The right side of the driving surface 180 of the spinning driving wheel 113 drives the friction disk 110 in an opposite direction, hence propelling the yard maintenance apparatus 1 backward.

The propelling speed of the yard maintenance apparatus 1 is varied by adjusting the position of the friction disk 110 relative to the driving surface 180. The tangential velocity on the driving surface 180 increases as the distance from the center of rotation is increased. Therefore, as the friction disk 110 is moved radially outward with respect to the axis of rotation of the driving wheel 113, its angular velocity increases.

In the neutral position, when no motion of the rear wheels 3 is required, the friction disk 110 is positioned near the axis of rotation of the driving wheel 113 (FIGS. 20-21). In this position, the yard maintenance apparatus may be pushed or pulled around manually. Unlike conventional friction drive systems, the central recessed portion 143 of the driving surface 180 causes the friction disk 110 to become disengaged from the driving surface 180 without the need for additional lifting mechanism for disengagement. This prevents unnecessary wear of the friction disk 110 while in the neutral position.

The concave profile of the central recessed portion 143 also permits a smooth engagement between the friction disk 110 and the driving surface 180 (FIG. 20). As the friction disk 110 is moved outwardly from the center of rotation of the driving wheel 113 the traction force between the friction disk 110 and the driving surface 180 disk is developed gradually and slippage is minimized as the rotational speed of the friction disk 110 is increased. This feature further reduces wear of the friction disk 110.

When the friction disk 110 first engages the driving surface 180 the spring 119 becomes compressed and urges the friction disk 110 against the driving surface 180. The tension in the spring 119 can be adjusted by turning the knob screw 97 to maintain a suitable force of engagement between the friction disk 110 and the driving surface 180 such as to avoid slippage. The spring 119 acts on the axle 111 via the hardened steel ball 120 and the partition disk 118.

A significant amount of heat can be generated by the self-propelling system 179 due to friction during propelling of the apparatus for extended periods of time. The elevated temperature generated within and around the components can accelerate wear of the friction disk 110 and is often the main cause of premature failure of both the driving wheel 113 and the friction disk 110. In order to diminish this problem, radial fins 123 on top of the driving wheel 113 are used to effectively dissipate heat and also serve as impellers to promote circulation of the surrounding air and thereby cooling the self-propelling system 179.

From the foregoing description, it can be seen that the present invention comprises a yard maintenance apparatus used for mowing grass, clearing leaves and blowing snow. It will be appreciated by those skilled in the art that obvious changes can be made to the embodiments described in the foregoing description without departing from the broad inventive concept thereof. It is understood, therefore, that this invention is not limited to the particular embodiments disclosed, but is intended to cover all obvious modifications thereof which are within the scope and the spirit of the invention as defined by the appended claims. 

1. A blade assembly for rotatably mounting to a yard maintenance apparatus comprising: a first elongated support member for rotatably mounting to a drive shaft; two shovelling surfaces disposed at opposite ends of the first elongated support member extending from the first elongated support member downwardly and laterally opposite one from the other; wherein each shovelling surface has a lower edge with a cutting edge, an upper edge, an inner edge and an outer edge.
 2. A blade assembly according to claim 1, further comprising an upwardly extending vane adjacent the upper edge of the shovelling surface.
 3. A blade assembly according to claim 2, wherein the vane also extends outwardly beyond the outer edge of the shovelling surface.
 4. A blade assembly according to claim 2, further comprising a vane extension secured to the vane and extending outwardly beyond the outer edge of the shovelling surface.
 5. A blade assembly according to claim 1, wherein the cutting edge of the lower edge of the shovelling surface extends outwardly beyond the outer edge of the shovelling surface.
 6. A blade assembly according to claim 1, wherein each shovelling surface is planar.
 7. A blade assembly according to claim 1, wherein each shovelling surface is curved.
 8. A blade assembly according to claim 1, wherein the outer edge of each shovelling surface has a circular vertical projection.
 9. A blade assembly according to claim 1, wherein the outer edge of each shovelling surface has an outer flange.
 10. A blade assembly according to claim 9, wherein the outer flange has a cutting edge.
 11. A blade assembly according to claim 1, wherein the inner edge of each shovelling surface has an inner flange.
 12. A blade assembly according to claim 11, wherein the inner flange has a cutting edge.
 13. A blade assembly according to claim 1, wherein each shovelling surface is divided into a first stage and a second stage.
 14. A blade assembly according to claim 13, wherein the first stage of each shovelling surface is connected to the drive shaft via the first elongated support member and the second stage of each shovelling surface is connected to the drive shaft via a second elongated support member.
 15. A blade assembly according to claim 13, wherein the first stage defines a curved shovelling surface portion and the second stage defines a planar shovelling surface portion.
 16. A blade assembly for rotatably mounting to a yard maintenance apparatus comprising: a first elongated support member for rotatably mounting to a drive shaft; two shovelling surfaces disposed at opposite ends of the first elongated support member extending from the first elongated support member downwardly and laterally opposite one from the other; each shovelling surface having a lower edge with a cutting edge, an upper edge, an inner edge and an outer edge; a vane extending upwardly adjacent the upper edge of the shovelling surface and further extending outwardly beyond the outer edge of the shovelling surface; wherein the cutting edge of the lower edge of the shovelling surface extends outwardly beyond the outer edge of the shovelling surface.
 17. A combination yard maintenance apparatus for lawn mowing, leaf clearing and snow blowing comprising the blade assembly of claim 1, wherein the combination yard maintenance apparatus further comprises: a chassis having ground wheels, an inlet and a discharge outlet; a motive power source mounted on the chassis; and, a drive shaft coupled to the power source and extending along a vertical axis; wherein the blade is coupled to the drive shaft.
 18. A combination yard maintenance apparatus according to claim 17, wherein the chassis comprises a cylindrical cavity having a vertical longitudinal axis in which the blade assembly is rotatably mounted.
 19. A combination yard maintenance apparatus according to claim 18, wherein the cylindrical cavity is divided into an upper portion and a lower portion by an annular flange, wherein the vane is adapted to rotate within the upper portion of the cavity and each shovelling surface is adapted to rotate within the lower portion of the cavity.
 20. A combination yard maintenance apparatus according to claim 18, wherein the chassis comprises a scraper plate mounted under the chassis conforming partially to the contour of the cylindrical cavity.
 21. A combination yard maintenance apparatus according to claim 17, wherein the inlet comprises a funnel-shaped deflector.
 22. A combination yard maintenance apparatus according to claim 17, wherein the discharge outlet comprises a movable deflector for changing the discharge direction.
 23. A combination yard maintenance apparatus according to claim 17, further comprising a self-propelling mechanism.
 24. A combination yard maintenance apparatus according to claim 17, wherein the source of motive power is a gasoline engine.
 25. A combination yard maintenance apparatus according to claim 17, further comprising a clutch for engaging and disengaging the blade assembly from the drive shaft.
 26. A clutch mechanism for engaging and disengaging an input shaft to and from an output shaft comprising: a first threadable engagement associated with the input shaft; a second threadable engagement associated with the output shaft; an initiator for inducing the engagement of the first and second threadable engagements.
 27. A clutch according to claim 26, wherein the first threadable engagement comprises an externally threaded portion on the input shaft; and the second threadable engagement comprises an output driver having an internally threaded portion; whereby the first threadable engagement is engaged to the second threadable engagement when the rotation of the input shaft relative to the output shaft is in a working direction.
 28. A clutch according to claim 27, further comprising: a drive head connected to the input shaft such that when the output driver is fully engaged to the input shaft, the drive head is in contact with the output driver via corresponding mating surfaces; wherein the corresponding mating surfaces define a one-directional locking system which prevents further rotation of the drive head in the working direction relative to the output driver.
 29. A clutch according to claim 28, wherein the one-directional locking system comprises a step defined on the mating surface of the drive head and a cooperating step defined on the mating surface of the output driver.
 30. A clutch according to claim 28, wherein the drive head is connected to the input shaft by a key and keyway arrangement.
 31. A clutch according to claim 27, wherein the output driver is connected to the output shaft by a splined coupling.
 32. A clutch according to claim 26, wherein the initiator is cable-activated.
 33. A clutch according to claim 32, wherein the initiator comprises a cable attached to a riser that is in contact with the output driver; wherein the riser is also in biased contact with a stator such that movement of the riser relative to the stator causes movement of the output driver and induces the engagement of the first and second threadable engagements.
 34. A clutch according to claim 33, wherein the riser is in rotatable contact with the stator about a central axis; and the mating surfaces between the riser and the stator are adapted such that rotational movement of the riser about the central axis relative to the stator causes longitudinal movement of the output driver along the central axis.
 35. A clutch according to claim 34, wherein the mating surfaces have a profile that varies in the direction of the central axis.
 36. A friction-drive self-propelling system comprising: a driving wheel coupled to a motive power source and having a driving surface normal to its axis of rotation wherein the driving surface has a central recessed portion; a driven friction disk having an axis of rotation transverse to the axis of rotation of the driving wheel; the friction disk having an outer peripheral surface being tangentially engageable with the driving surface; wherein the friction disk is laterally movable along its axis of rotation between a neutral position and a propelling position such that in the neutral position the friction disk is aligned with the central recessed portion and thereby disengaged from the driving surface.
 37. A friction-drive self-propelling system according to claim 36, wherein the driving wheel further comprises a radial fin.
 38. A friction-drive self-propelling system according to claim 36, wherein the friction disk is laterally movable by cable and lever mechanism.
 39. A friction-drive self-propelling system according to claim 36, further comprising a tension adjustment for adjusting a force of engagement between the driving wheel and the driven friction disk.
 40. A friction-drive self-propelling system according to claim 36, wherein the speed of rotation of the driven friction disk is adjusted by lateral movement of the driven friction disk to alter the distance between the propelling position and the central recessed portion of the driving surface. 